package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import io.lettuce.core.api.async.RedisGeoAsyncCommands;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        /* 解决缓存击穿
           Shop shop = queryWithPassThrough(id);*/

        /* 互斥锁解决缓存击穿
         Shop shop = queryWithMutex(id);*/

        /* 使用逻辑过期解决缓存击穿问题
           Shop shop = queryWithLogicalExpire(id);*/
        // Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);

        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.SECONDS);
        if (shop == null){
            return Result.fail("店铺不存在!!!");
        }
        return Result.ok(shop);
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    // 解决缓存击穿采用逻辑判断方式
    public Shop queryWithLogicalExpire(Long id){
        String key = CACHE_SHOP_KEY+id;
        // 1.从redis里面查询缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在
        if(StrUtil.isBlank(shopJson)) {
            // 3.不存在，直接返回null
            return null;
        }
        // 4.命中缓存，需要先将JSON反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();

        // 5.判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())) {
            // 5.1 未过期，直接返回店铺信息
            return shop;
        }
        // 5.2 已过期，需要缓存重建
        // 6.缓存重建
        // 6.1 获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        // 6.2 判断是否获取锁成功
        if(isLock) {
            // 6.3 成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    // 缓存重建
                    this.saveShopToRedis(id,30L);
                }catch (Exception e){
                    throw new RuntimeException(e);
                }finally {
                    // 释放锁
                    unlock(lockKey);
                }
            });
        }

        // 7.未获得锁就拿取过期的缓存信息
        return shop;
    }

    // 仅仅解决缓存穿透的问题
    public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY+id;
        // 1.从redis里面查询缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在
        if(StrUtil.isNotBlank(shopJson)) {
            // 3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson,Shop.class);
            return shop;
        }
        // 判断命中的是否为空值
        if(shopJson != null){
            // 返回错误信息
            return null;
        }
        // 4.不存在就去MySQL里面找
        Shop shop = getById(id);
        // 5.查不到返回错误
        if(shop==null){
            // 解决缓存穿透的问题，加入空值判断逻辑
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        // 6.存在，写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        // 7.返回
        return shop;
    }

    // 解决缓存击穿的问题（同时包含解决缓存穿透的问题)
    public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY+id;
        // 1.从redis里面查询缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在
        if(StrUtil.isNotBlank(shopJson)) {
            // 3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson,Shop.class);
            return shop;
        }
        // 判断命中的是否为空值
        if(shopJson != null){
            // 返回错误信息
            return null;
        }

        // 4.实现缓存重建
        // 4.1 获取互斥锁
        String lockKey = LOCK_SHOP_KEY+id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            // 4.2 判断是否获取互斥锁成功
            if(!isLock){
                // 4.3 获取互斥锁失败，就休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }

            // 4.4 获取互斥锁成功，根据id查询数据库
            // 4.不存在就去MySQL里面找
            shop = getById(id);
            // 5.查不到返回错误
            if(shop==null){
                // 解决缓存穿透的问题，加入空值判断逻辑
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            // 6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            // 7.释放互斥锁
            unlock(lockKey);
        }
        // 8.返回
        return shop;
    }

    // 基于setnx制作互斥锁解决缓存击穿问题
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key,"1",10,TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    // 释放锁的操作
    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }

    // 基于逻辑过期方案解决缓存击穿问题：将店铺信息封装进redis
    public void saveShopToRedis(Long id , Long expireSeconds) throws InterruptedException {
        // 1.查询商铺信息
        Shop shop = getById(id);
        // 2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        // 3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id, JSONUtil.toJsonStr(redisData));
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id == null){
            return Result.ok("店铺id不能为空");
        }
        // 1.更新数据库
        updateById(shop);
        // 2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY+id);

        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.查看是否需要根据经纬度查询
        if (x == null || y == null) {
            // 不需要坐标查询，直接在数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }

        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        // 3.查询redis，按照距离分页查询  GEOSEARCH key BYLONLAT x y BYRADIUS radius WITHDISTANCE
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );

        // 4.解析出店铺id;
        if (results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from) {
            return Result.ok(Collections.emptyList());
        }
        // 4.1 截取出from-end的部分
        ArrayList<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 4.2 获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3 获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5.根据id查询
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD (id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6.返回
        return Result.ok(shops);

    }
}
